Inhibition of Beta-Glucuronidases from the Human Gut Microbiome

The human gut microbiome encodes 4.8 million genes, some of which are expected to create a wealth of catalytic enzymes functions in the gastrointestinal (GI) tract. We have focused on gut microbial beta-glucuronidase (GUS) enzymes because they cause dose-limiting GI toxicity of many drugs, including chemotherapeutics. We have created an atlas of all the GUS proteins in the human gut microbiome, termed the GUSome. A focal question asks how selective inhibition of gut microbial GUS enzymes can alleviate the toxic side effects of chemotherapeutics and pain medicines. Here we show that novel analogs of UNC10201652, a previously characterized GUS inhibitor, block the activity of E. coli GUS, S. agalactiae GUS, and C. perfringens GUS. Each of these enzymes contain an active site loop (Loop 1) that plays a key role in processing small-molecule drug-glucuronides. Kinetic analysis revealed that the inhibitors display differential inhibition across the distinct GUS enzymes examined. We show that GUS enzymes are differentially inhibited by analogs of UNC10201652 by characterizing the distinct substrate-dependent slow-binding kinetics of these piperazine-dependent inhibitors. The characterization of these piperazine-containing GUS inhibitors may improve the outcomes of essential chemotherapeutics.Bachelor of Scienc